Many electronic devices are sensitive to electrostatic discharge (ESD) and other forms of voltage spikes. An ESD event is a sudden flow of electricity between two or more objects. The electrical flow can be initiated in several ways, such as electrical contact, human contact, or an accidental discharge during manufacturing or assembly. The static electricity developed by walking across a carpet can be enough to damage some devices, where static electricity often has very high voltage. In many cases, an ESD event will damage or destroy one or more electronic components in an electronic device, and ESD events are common.
Various techniques are used to prevent electronic device damage due to ESD events. For example, manufacturers may utilize electrostatic protective environments that are essentially free of static electricity. This can involve several measures, such as avoiding the use of highly charging materials, grounding objects and/or workers, and controlling humidity. Many electronic devices are transported in special containers that help prevent damage from ESD events, such as anti-static bags that include partially conductive plastics or other conductive materials. However, it may be difficult or impossible to prevent ESD events for electronic devices in use. For example, an electronic device included in a motor vehicle or a hand held device is exposed to many different conditions, so prevention of ESD events is difficult. Some electronic devices include design features to protect electronic components, but such protection has limits. On-chip ESD discharges can also damage discrete components, and other types of ESD protection are more appropriate for on-chip ESD discharges.
Some electronic devices include two or more protected circuits that operate at different voltages, so the electrostatic discharge protection measures are typically designed for different trigger voltages appropriate for the operating voltage. A “protected circuit” is a circuit or sub-circuit of the electronic device that has an ESD circuit for protecting the “protected circuit” from an ESD event. Integrated circuits are used for a wide variety of uses, and many of those uses demand the integrated circuit include components that operate at different voltages, with some components operating at relatively low voltages, others at medium voltages, and still others at higher voltage. The electrostatic discharge protection measures are often individually designed for protected circuits operating at different voltages, so protected circuits operating at each operating voltage may have an electrostatic discharge protection device with a different design. The design of multiple different electrostatic discharge protection devices requires more input than the design of a single type of electrostatic discharge protection device, and the use of several different types of electrostatic discharge protection devices in a single electronic device may require additional manufacturing steps for some of the ESD circuits but not for others. Additional manufacturing steps generally increase the cost of an electronic device.
Accordingly, it is desirable to provide electronic devices with an electrostatic discharge protection device with a trigger voltage that can be adjusted with a minor change in the ESD protection device, and methods of producing the same. In addition, it is desirable to provide electronic devices with ESD protection devices having a rapid trigger response time and a high current capacity, and methods of producing the same. Furthermore, other desirable features and characteristics of the present embodiment will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.